•
•From
theory:
–Pressure
(P) and density (r) must increase with depth
•Weight
of overlying gas compresses lower material -- “Hydrostatic
equilibrium”
–Temperature
(T) must increase with depth
•Energy
is flowing out of the sun – and it flows from hot to cold -- so hot
inside
–Numerical
modeling of details let us calculate T(r), r(r), P(r)
–
•From
observations of “oscillations” or “solar
seismology”
–The
sun oscillates like a bell (or the air in an organ pipe)
–The
frequency depends upon sound speed, and that depends upon T(r), r(r), P(r)
–Observations
from the “Global Oscillation Network Group (GONG) telescopes.
–
•From
interpreting the spectrum using Kirchoff’s laws
–In
general the spectrum of the Sun looks like continuous emission
•This
must come from a solid – or a very dense gas
–We see
many dark absorption lines in the solar spectrum
•This
must come from cooler gas between us and the hot dense gas